Indoor Factory Noise calculates noise inside factory buildings. The model is based on the German VDI 3760. Point, line, and area sources describe the sources; inside walls and absorption areas describe the objects inside the factory building. The industrial building itself has provisions for the geometry and for describing the absorption on the outside walls and the scattering inside the building. Calculations generate feed data for the transmission to the outside environment or to display a sound propagation curve inside the building, or are used for the final data for printed and plotted output.